An international team led by Radboud University physicists has discovered that reversing the poles of magnets must be possible without a heating or a magnetic field.. A strong pulse of light can have a direct effect on the strong quantum mechanical 'exchange interaction', therefore changing the magnetism (Nature Communications, 16 September 2015).
In 2007, Professor Rasing and his group at Radboud University showed for the first time that fast pulses of laser light can reverse the poles of magnets.
Ref: Ultrafast optical modification of exchange interactions in iron oxides. Nature Communications (2015) | DOI: 10.1038/ncomms9190